The present invention relates to an improved fire ring holder to hold a fire ring in a cylinder opening of a gasket.
Gaskets are used as a seal between the engine block and cylinder head of an internal combustion engine. Cylinder head gaskets typically extend around the cylinder bores to provide a combustion seal, maintaining the high temperature gases of combustion within a cylinder bore. The gasket bears the load from a bolted connection of the engine block and cylinder head components and relies upon that load to provide a seal.
It is known to provide cylinder head gaskets with a fire ring adjacent the cylinder bores to protect the actual gasket body from the deleterious effects of the combustion environment. Typically, an annular metallic flange has been provided for retaining the fire ring to the gasket body. This flange is generally U-shaped in cross-section, having upper and lower legs which extend continuously around a cylinder bore and engage upper and lower surfaces of the gasket. The fire ring is enclosed within a trough of the holder defined by the U-shaped cross-section.
Up to 30% of the clamping force from the bolted connection of the mechanical components is used to secure such flanges to the gasket. Thus, this portion of the force is not available to prevent leakage from the various seals. A high force is necessary due to the relatively large contact area between the mechanical components and the flange legs.
Moreover, such flanges require a large amount of material and are associated with high tooling and manufacturing costs. The fire ring must be manually loaded into the U-shaped trough. Then a closing die must be used which forms and presses the flange legs over the ring and the gasket body. A flattening operation is then required which must be inspected to confirm that the flange is at a pre-established height.
Further, by enclosing the fire ring within a flange, the possible cross-sectional diameter of the ring is limited by the thickness of the gasket minus the thickness of each of the flange's legs. Additionally, it is difficult to inspect the fire ring. Inspections using expensive electronic equipment have had only limited success.